1. Field of the Invention
This invention relates generally to a device and method for occluding a body duct and, more specifically, this invention relates to a device and method for reversibly occluding such a duct for preventing passage of duct contents therethrough. The invention is especially applicable to reversible occlusion of the vas deferens in order to achieve male sterilization.
2. Description of the Prior Art
A number of methods are available to effect either permanent sterility (e.g. sectioning and ligation of the Fallopian tubes or the vas deferens) or reversible sterility (e.g. hormonal contraceptives, such as the "birth control pill", intrauterine devices, the cervical diaphragm or vaginal creams, foams and suppositories). However, such means are either not sufficiently effective in inducing sterility, or have a number of undesirable associated side effects. Permanent sterility may be undesirable to many men and women. At present, no consistently effective reversible method of sterilization is available to the male.
Vasectomy (i.e. sectioning and ligation of the vas deferens) has gained popularity in recent years. However, the procedure is generally considered to be irreversible. Thus, vasectomy is not universally desirable.
Although a number of allegedly reversible vas deferens occlusion devices and methods have been proposed, these are generally not reliable. In most cases, such procedures do not completely prevent sperm passage through the vas deferens, and/or are not consistently reversible. Some prior occlusion devices are complicated in design, or tend to result in irreversible damage to the vas deferens during implantation. Some methods require complete sectioning of the vas deferens, which seriously lessens the chances for successful reversal.
Some prior occlusion devices are inflexible, and thus tend to result in injury to the vas deferens and nearby organs during exercise.
Still other devices result in permanent adhesion or other attachment of the device to the vas deferens so that the functional activity of the vas deferens is permanently altered. This in turn decreases the probability of successful reversal of the sterilization procedure.
One prior intravasal occlusion device and method is described in Lee U.S. Pat. No. 3,589,355. The device described in the Lee patent comprises a single intravasal plug with a filiform thread attached to one of its ends. The plug is introduced to the vas by means of a needle, with the thread extending through the vas wall. The thread is then tied around the vas in order to hold the plug in place.
However, is has been reported that the device and method of the Lee patent are not fully effective in blocking the passage of sperm through the vas deferens. Further, ligature of the vas deferens by the Lee method has a strong tendency to damage the vas, with the result in some cases of irreversible sterilization.